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Classical aversive conditioning of catecholamine and corticosterone responses
D L Pitman1, B H Natelson, J E Ottenweller
1New Jersey Medical School.
Summary
This study found that learned fear conditioning in rats can alter epinephrine levels, but not norepinephrine or corticosterone. These findings suggest that while stress hormone responses can be learned, they are complex and not always consistently observed.
Area of Science:
- Neuroscience
- Behavioral Endocrinology
- Psychophysiology
Background:
- Previous research suggested potential conditional increases in sympathoadrenal stress hormones.
- Earlier studies lacked rigorous experimental control, necessitating further investigation.
Purpose of the Study:
- To investigate conditional changes in stress hormones using a controlled design.
- To determine if fear conditioning influences norepinephrine, epinephrine, and corticosterone levels.
Main Methods:
- Rats were subjected to differential fear conditioning in a tether-type apparatus.
- Chronic catheterization enabled pre- and post-stimulus blood sampling without disturbing the animals.
- Norepinephrine, epinephrine, and corticosterone levels were measured.
Main Results:
- No evidence of conditional changes in norepinephrine or corticosterone was observed.
- Differential conditioning of epinephrine responses was detected.
- Conditional increases in epinephrine were not consistently observed following conditioned stimulus probes (CS+).
Conclusions:
- Learned changes in hormonal stress responses are supported by these data.
- The difficulty in obtaining clear-cut conditional changes in these visceral systems remains an open question.
- Further research is needed to understand the complexities of learned hormonal responses to stress.